Biostrome: a bedded mass of rocks that composed entirely of skeletal remains

Bird’s-eye structure: lensoid pores that are larger than the normal intergranular spaces. May be filled with sparry cement and are typically observed fine-grained limestones and dolomites. Synonymous with fenestral fabric which, when laminated, is usually formed by intertidal cyanobacterial mats.

Birefringence: an optical property of crystal in which a single ray of light can be split into two rays of unequal velocities and each vibrating in different directions.

Bladed: describes an elongated and flattened sparry calcite cement with a length-to-width ratiobetween 1.5:1 and 6:1

Cyanobacteria and Cyanobacterial Mat: were known as “blue-green algae" and “blue-green algal" mats, but are now identified as large photosynthetic bacteria. Range from blue-green, yellow-green, brown, or even reddish-purple. Many are motile. Often produce slime sheaths. Cyanobacteria can produce thick and extensive mats. Some of the most extensive of these occur in the intertidal zone of the coast of the Khor al Bazam lagoon in the United Arab Emirates.

D

Detrital: describes a mineral or other substance (organic matter for example) that exists (or existed) as a sedimentary particle, subject to transport within and across surficial environments.

Diagenesis: the sum of physical and chemical processes that affect a sediment following deposition; the vague and ill-defined boundaries between diagenesis and syn-sedimentary processes, between diagenesis and weathering, and between diagenesis and metamorphism reflect the gradational character of these processes.

Drusy cement: sparry calcite cement lining the pores wall of a limestone, it has the characteristic of increasing in crystal size toward the pore center

Dunham classification: carbonate rock classification put forth by Dunham (1962); widely adopted in the international petroleum industry because its simplicity and ease of application with handspecimens.

E

Effective porosity: the interconnected void space in a rock that contributes to fluid flow or permeability in a reservoir rock.

Epigenetic: minerals formed after deposition, at low temperature and pressure changes or transformations affecting sedimentary rocks subsequent to compaction

Epifaunal: refers to benthic organisms that live attached to the sediment surface or to other organisms on the sediment surface.

Epiphyte: an organism that lives attached to a biologic substrate; may be either pelagic or benthic

Equant: describes the shape of sparry calcite cement crystals that have a length-to-width ratio of less than 1.5:1

Fabric: rock fabrics usually describe the relation between grains in terms of size, shape, contacts and orientations

Fenestral fabric: pores that are large compared to the size of expected intergranular pores, forming an elongate or domal shape parallel with bedding plane; often associatated with cyanobacterial mats. These fabrics are know as laminar birdseye limestones too. May be cement-filled.

Fibrous: an elongated crystal with length-to-width ratio greater than 6:1

Floatstone: a mud-supported limestone rich with skeletal fragment in which 10% or more of the grains are greater than 2 mm in diameter (introduced by Embry and Klovan, 1971)

Folk Classification: One of the most widely used limestone classifications, it is based on the matrix/cement ratio and the identity of the main allochems.

Framestone: organisms building a rigid framework associated with cement and pore space. (introduced by Embry and Klovan, 1971)

G

Geopetal structure: a rock fabric or structure that indicates the gravitational direction of the rock at the time of deposition, for example, internal sediment accumulated within the cavities of gastropod or brachiopod shells, that were then subsequently filled by sparry cement.

Grain dissolution: removal of a detrital component by transfer of its material into aqueous solution

Grain-supported texture: refers to a limestone fabric in which the volume of the grains exceeds the mud. Grains usually in contact with each other (introduced by Dunham 1962)

Grainstone: a limestone with sand-size grains with very little or no mud (introduced by Dunham 1962)

Grapestone: a term used to describe a limestone composed of aggregated of carbonate particles.

Gravitational cement: concentration of calcitic cement on the bottom side of grain. It forms due to the gravity and usually indicate a vadose or above the water table zone. Syn.: pendant or microstalactitic cements

gypsum: a highly insoluble evaporite mineral composed of hydrous calcium sulfate. It is the first to precipitate from evaporating seawater.

H

Hardground: a region of the seafloor that is cemented in situ

High-magnesium calcite: variety of (CaCO3) that has at least 2 to 5 mole percent of the Ca in the crystal lattice substituted by Mg.

ichnofacies: concept developed by Adolph Seilacher (1967) at Tubingen University as a paleontological tool to analyze assemblages of trace fossils and determine ancient depositional settings and facies of sedimentary rocks.

Ichnofossil: an expression of the alteration of the depositional fabric of in sedimentary rocks by living organisms.

Ichnofauna: living organisms that change the depositional fabric of in sedimentary rocks by burrowing them or constructing edifices within the sediment.

Impregnation medium: a relatively low viscosity material, typically a colored plastic, that is injected into the pore spaces of a rock before thin sectioning and then hardened by a curing process; such treatment makes the rock more stable during cutting and grinding, renders the porosity more visible in transmitted light microscopy, and enables the petrographer to reliably distinguish the natural porosity (colored) from artificially-induced porosity created during the thin sectioning process (filled with the clear medium used to bond the sample to the glass substrate).

Inclusion: gas- or fluid-filled holes or crystals encased within a larger crystal of different mineralogy

Infaunal: refers to benthic organisms that live within rather than on the sediment surface

Interparticle porosity: refers to void space between particles (intercrystal porosity and intergranular porosity can be used as well)

Intraparticle porosity: refers to void space within a particle (intracrystal porosity and intragranular porosity can be used as well)

Intraclast: sedimentary particle formed by reworking of lithified materials formed within the depositional environment

Meniscus cement: refers to calcite cement that precipitated at or near the grain contacts in vadose zone. The curverlinear fabric captured by the crystals reflects the curverlinear meniscus formed by water trapped in the vadose zone.

Mesogenetic: ocuuring during the time interval in which rocks or sediments are buried at depth below the major influence of processes directly operating from or closely related to the surface

micrite: a term coined by Bob Folk to describe microcrystalline calcite usually less than 5 micron millimeter, found as matrix in many limestones, see lime mud

micrite envelope: a dark thin layer of micrite found around an allochem, usually associated with the micrite filling of borings produced by microendolithic organisms. A term coined by Robin Bathurst in 1966.

Microcrystalline: describes a texture of a rock consisting of very fine grain size, can not bee seen by naked eye.

Mud-supported: refers to the fabric of a limestone (mudstone or wackestone) in which the grains are floating in a micritic matrix. Grains make up a lesser volume of the rock than does the mud (introduced by Dunham 1962)

N

Nektonic: that portion of the biota that are active swimmers, as opposed to merely pelagic

Neomorphism: a broad term for all diagenetic transformation of a mineral and itself or a polymorph, including changes in size and shape without changes in chemical composition.

Neomorphic spar: the transformation of micrite into spar in neomorphism processes

O

Oncoid: a grain coated by cyanobacteria (or blue-green algae)commonly with a diameter greater than 2 mm, they are spherical to sub spherical form of microbial/algal showing irregular laminations. Also known as algal pisolites, very closely resemble vadose pisolites.

Oncolite: a rock that composed of oncoids

Ooids: a carbonate grains which commonly range in diameter between 0.25 to 2.00 mm. They are spherical to ellipsoidal with a nucleus covered by one or more concentric coatings that under microscope show a series of concentric laminations

Oomicrite: a limestone composed of ooids floating in a micritic matrix (Folk, 1959)

Ooze: a fine-grained sediment (sub-sand size particles) of either calcareous or siliceous composition; typically dominated by the skeletal remains of nannoplankton.

Overgrowth: cement that is in optical continuity with the detrital grain on which it nucleated; the most common morphology for authigenic quartz; also observed for cements nucleated on echinoderm fragments.

Pencontemporaneous: generally referring to a any diagenetic feature such as cement or replacement that formed at the time of deposition

Petrography: the study of microscopic feature of rocks, such as microfossils, diagenesis and porosity

Phreatic zone: is the layer(s) of rocks below the water table in which the interstitial water will freely flow from pores within the rocks.

Pisoid: spherical or elliptical accretionary coated particles, they are similar to ooids, both have a fabric of radial fibrous crystals with a concentric pattern but pisoids usually larger in size (2.00 to 10.00 mm) and less regular. These grains may be formed by the dirrect chemical precipitation of calcium carbonate, but some might formed by a biochemical algal-encrusting process.

Primary porosity: pore space between detrital grains, existing at the time of deposition

Prismatic crystal: it is very common crystal habits, an elongated crystal with a pencil-like shape

Protodolomite: dolomite with crystalline calcium and magnesium disorder within its structure

Provenance: the ultimate lithologic source of a detrital grain or grain assemblage; seldom ascribed to a particular rock type or formation, provenance is usually described in more general lithologic terms such as “plutonic”, “mixed sedimentary”, or “mafic volcanic” or, equally valid, in terms of tectonic setting such as “arc” or ; a commonly conflated with the penultimate “source” of the sample the “depositional environment”---a misconception that the student of sandstone petrology must steadfastly avoid.

Pseudospar: a recrystallized calcite with size range between 10.0 to 50.0 micron millimeters. Generally, micrite is neomorphically replaced by microspar (5.0-10 micron m), or pseudospar, they both are characterized by patches of irregularly shaped crystals

Q

R

Radiated: an aggregate of acicular crystals that radiate from a central point, for example, aragonitic ooids

Radiaxial-fibrous cement: a rodlike crystals usually found as cavity filling cement, radiating away from the cavity wall.

Recrystallize: a somewhat outdated term meaning, literally, “to crystallize again”. Typically refers to a process in which an unstable precursor mineral is dissolved and the space is filled by a newly formed phase of the same mineralogy; a common example would be recrystallization of Mg-calcite to low-Mg calcite; when the newly formed phase is also a different mineral the process is known as ‘replacement’. Historically, this term came into use to describe the obvious textural modifications that occurred in diagenesis, but before much was understood about the mechanism by which this process took place. The notion that this process involves some sort of solid state reorganization of the crystal lattice is generally falling into disfavor, ‘replaced’ by the idea that the process is largely accomplished by dissolution and subsequent precipitation.

Replacement: precipitation of an authigenic phase into a space formerly occupied by a detrital grain or an earlier authigenic phase; distinguished from cements that precipitate into primary pore space.

Reef: a massive moundlike structure, built by calcareous organisms, especially corals, sponges and calcareous algae. It is a wave-resistant body standing above the surrounding sediments

Reef limestone: a limestone composed of skeletal remains of reef-building organisms, such as corals, sponges, bryozoans and calcareous algae.

Relict texture: a ghost of original texture that remains after partial or total replacement or recrystallization

Reservoir rock: a porous and permeable rock that has the potential to trap oil and gas

Reworked: describes any components (grains, fossils, lithoclasts ..etc.) that is derived from an older sedimentary formation and incorporated in a younger one.

Rhodolith: an irregular laminated calcareous nodule, usually composed of encrusting coralline red algae arranged in more or less concentric layers about a core.

Rudstone: a limestone with a coarse-grain and sparry cement texture, 10% or more of the grains are greater than 2 mm (Embray and Klovan, 1971)

S

Secondary porosity: pore space formed by dissolution of a detrital or authigenic mineral; the least ambiguous secondary pores are those within partially dissolved detrital grains; documentation of cement dissolution is, in contrast, highly problematic.

Silicification: replacement of a carbonate component by silica, generally resulting in the formation of microcrystalline quartz, chalcedony or opal, which may fill pores or replace existing component.

Stromatactics: a spar body common in Paleozoic muddy carbonate sediments, it is result of centripetal cementation in a cavity system. Its origin is still debatable

Stromatolites: a laminated, mound biosedimentary structure, precipitation as result of the growth of cyanophytes.

Stylolite: a grossly planar sutured structure that cuts through depositional rock components, and also some diagenetic components. Stylolites arise from simultaneous compaction and dissolution and may develop substantial accumulations of insoluble materials.

Subhedral: describes a crystal that manifests only partial development of its characteristic crystal faces

Superficial ooid: an ooid with a very thin cortical coating

Syndeposition: processes that occurred during deposition. See Penecontemporaneous

Syntaxial cement: cement that adopts the crystal orientation of its nucleation substrate; an overgrowth. In limestones such cements are common on echinoderm fragments.

T

Tabular: a flat body has large area (crystal or skeletal grain) relative to thickness, generally thicker than platy.

Texture: the texture of a rock is the size, shape and arrangement of the particles (crystals, allochems, litoclasts..etc.)

Tufa: a terrestrial carbonate rock with spongy texture, formed around springs, lakes, or along streams. Synonymous with travertine.

Test: an external shell secreted by some protozoans such as foraminifera. Tests can be calcareous, siliceous, or agglutinated.

Twinning: an intergrowth of two or more crystals grains, so a plane through which one twin individual forms a mirror image of the other. There are several minerals that form prominent twins such as calcite and fluorite